How do you FIT a boolit or design it for a lever action with a deep throat?

[MBTcustom]

How would that sucker do at 100 yards? I also wonder how well it would feed.

Tim, ever think of turning a similar bullet from brass, seating in a case, and checking the feeding properties? Don't know how feasible it is to even turn a few from a bigger hunk of lead?

Brad, I make steel mockups for everything I do and every design I make. Read the OP. In it I said this

I turned said boolit out of tool steel to check fit and function in the rifle.

The problem with making mock ups out of lead, is that it deforms so easily that it can lie to you about where things are actually touching, and how much.
Sometimes I make the mockups out of aluminum if I am going to be sending them in the mail (standard envelope works perfectly then) but for my own use, it's steel.
Of course, this gives me static fit only. The only way to see how things really work is to shoot them and find out, but I have a few tricks there as well (cast a 1/2" X6" cylinder and turn them on the lathe) but usually, it's more practical to just have the thing cut by one of our awesome makers (Tom at Accurate is my favorite).
Anywho, that is definitely something that I do regularly, and it gets you closer than anything else.

[btroj]

Didn't see that you already made a dummy. I suppose I'm the dummy?

At some point ya just gotta go with your gut. Run makes some good points too, he often does. This time they were even clear stated!

[MBTcustom]

So basically, you're saying make sure the boolit:
1. Functions properly
2. Is the correct diameter
3. Looks pretty
In that order, and then hope it shoots accurately. (rabbit foot in pocket, salt over left shoulder, special boolit lube made of 4 leaf clovers and holy water)

LOL!

[btroj]

Sorta?

Function is mandatory for a leveraction. No bullets that don't feed are allowed unless you enjoy single shots with a tube magazine!

Diameter is a no brainer. Well, unless you enjoy mining barrels for lead.....

I don't shoot ugly bullets. Some look better than other but I do like the way some look in a loaded round. My father in law would say they just look right. He is right every so often.

Seriously, look at something like the 640 style nose in something around 240 gr. That is the nose style I would want. I also would want that smooth transition from nose to body, no sharp shoulder drive bands.

It need not conform to the shape of the throat as long as the nose design allows it to self center and easily enter the bore.

[MBTcustom]

Sorta?

Function is mandatory for a leveraction. No bullets that don't feed are allowed unless you enjoy single shots with a tube magazine!

Diameter is a no brainer. Well, unless you enjoy mining barrels for lead.....

I don't shoot ugly bullets. Some look better than other but I do like the way some look in a loaded round. My father in law would say they just look right. He is right every so often.

Seriously, look at something like the 640 style nose in something around 240 gr. That is the nose style I would want. I also would want that smooth transition from nose to body, no sharp shoulder drive bands.

It need not conform to the shape of the throat as long as the nose design allows it to self center and easily enter the bore.

So why not match the angle of the throat within that smooth transition? What would be the harm in doing so? Or are you saying it's so janky of a design that it really doesn't matter?

[TXGunNut]

Pretty is as pretty does. Learned that when I bought a Ruger Mk I over 30 yrs ago. On top of that it thinks Winchester Wildcat is Eley Match. You're thinking outside the box, Tim. I think it's worth a try.

[btroj]

It isn't that the rifle design makes the nose taper to ogive relationship irrelevant. I just don't know that "fit" requires that precise type of fit.

I'm no engineer, bullet designer, or what not but to my mind having those angles/surfaces match exactly could be detrimental. Let's think for a second. Of those surfaces match precisely the. What happens when the bullet hits the leade? The bullet suddenly has a massive amount of instant contact. It isn't gonna self center, it has too much contact. It also suddenly needs to engrave over a large area. The base is still going forward but the front end stopped. Bullet slump can easily take place and your rifle has a huge amount of room for that to do bad things.

If we have less initial contact between ogive and leade the bullet can center better. It also will engrave easier as the bullet is initially engraving a much smaller surface. Bullet slump issues might be minimized.

Again, think of fit as dynamic, not just static. We are looking to get a bullet to center in the bore and engrave straight. We aren't looking for a fit that will hold fast like a Morse taper. We also need to think of what happens when we pull the trigger. Our bullet can, and will, change shape. We can either have that happen in a manner conducive to accuracy or let it be willy nilly.

Like I said, I'm no engineer but these are the things my experiences have taught me. I want all my lever action bullets to have this kind of "fit".

[btroj]

http://castboolits.gunloads.com/show...fit-quot/page2

Here is a thread from a few years ago where I asked "What is fit". Some of the discussion is worth reading Tim, it helped from my opinions and made me change how I looked at things. Most of all it made me better at observing what was going on in my barrel.

[MBTcustom]

It isn't that the rifle design makes the nose taper to ogive relationship irrelevant. I just don't know that "fit" requires that precise type of fit.

I'm no engineer, bullet designer, or what not but to my mind having those angles/surfaces match exactly could be detrimental. Let's think for a second. Of those surfaces match precisely the. What happens when the bullet hits the leade? The bullet suddenly has a massive amount of instant contact. It isn't gonna self center, it has too much contact. It also suddenly needs to engrave over a large area. The base is still going forward but the front end stopped. Bullet slump can easily take place and your rifle has a huge amount of room for that to do bad things.

If we have less initial contact between ogive and leade the bullet can center better. It also will engrave easier as the bullet is initially engraving a much smaller surface. Bullet slump issues might be minimized.

Again, think of fit as dynamic, not just static. We are looking to get a bullet to center in the bore and engrave straight. We aren't looking for a fit that will hold fast like a Morse taper. We also need to think of what happens when we pull the trigger. Our bullet can, and will, change shape. We can either have that happen in a manner conducive to accuracy or let it be willy nilly.

Like I said, I'm no engineer but these are the things my experiences have taught me. I want all my lever action bullets to have this kind of "fit".

See that is completely opposite of the way I think of it Brad. The way I'm thinking is that we are going to have to move that boolit into alignment with the bore, becasue lets face it, we'll never have it exactly right. My thought is is that since we are shooting a very soft object into a very hard hole, and since we want that object to be centered by that hole and not deformed any more than necessary, then having broader contact and as much support as possible will help it align.
After all, we are darn close. I'ts not like we are throwing a boolit in the lead at a 30 degree angle or something. It more like we are off on the angle by a few arc seconds, and we are off on the alignment by a thousandth or less and we need to get that boolit the best chance to get aligned as possible.
One philosophy is to give it a long leadin angle and gently convince the boolit to comply. Another is to give you boolit a 90 degree angle on the shoulder and let it hit the rifling like a brick going through the bell of a trombone.
Neither one of these philosophy gives much support to the boolit, and they both allow the boolit to be deformed greatly before they get it moving. Perhaps people were to busy laughing at my "boolit deformation at launch" thread to really take a close look at the pictures and see if they could see what I see with a microscope. Pay special attention to the 311466 boolit. I'll give you a hint: (the rifling in my barrel was not a gain twist).

[MBTcustom]

http://castboolits.gunloads.com/show...fit-quot/page2

Here is a thread from a few years ago where I asked "What is fit". Some of the discussion is worth reading Tim, it helped from my opinions and made me change how I looked at things. Most of all it made me better at observing what was going on in my barrel.

I have read that thread, and I agree with almost everything written there. That is boolit shooting 101 and has been known for quite some time here.
But that's not what you yourself are advocating in this thread, so I can only assume that you have decided that thread is an example of what not to do?
What I am wondering here, is when perfect fit is impossible, and you have to jump, and you can't very easily make the brass fit the chamber without using a boolit that is ridiculously huge for the GD, and you have to jump 1/8" to the rifling how do you achieve dynamic fit?

Telling me to solve the problem with art, is not the answer I'm looking for. I'm hoping there is some sort of guidance that is based on something a person could actually measure.
I regret having started this in Leverguns forum. I have moved it to Molds Maintenance and design forum.

[Tom Myers]

If we have less initial contact between ogive and leade the bullet can center better. It also will engrave easier as the bullet is initially engraving a much smaller surface. Bullet slump issues might be minimized.

Again, think of fit as dynamic, not just static. We are looking to get a bullet to center in the bore and engrave straight. We aren't looking for a fit that will hold fast like a Morse taper. We also need to think of what happens when we pull the trigger. Our bullet can, and will, change shape. We can either have that happen in a manner conducive to accuracy or let it be willy nilly.

Like I said, I'm no engineer but these are the things my experiences have taught me. I want all my lever action bullets to have this kind of "fit".

btroj,

Your comments pretty much sum up the concepts that define the Design Paramaters of the new Cast Bullet Design ~ Ultimate software module.

Below are images of the design drawn by the software before I edited the dimensions to conform more to Tim's original specs.

The chamber fit image illustrates the minimum contact, maximum filling, self alignment concept inherent in the pramaters that govern the dimensions of the initial design.

The final bullet profile may be modified in many different manners and still conform to the original design paramaters.

Although I must admit that a practical, vaiable bullet designed to fit this short throat, continuous tapered lead is a challenge to both the softare and the designer.

P.S. One thing that I just realized about this design is that, as indicated on the bullet sketch, the Center of Pressure and the Center of Gravity almost perfectly coincide. Theoriticaly, this should result in a very stable, accurate, medium range, target bullet

[MBTcustom]

You know Tom, I'm starting to get real jealous of that program ya got there. Sure makes pretty pictures!
Thank you for doing this!

OK, so we have two theoretical options that Tom has drawn up.

One has a tapered lead in (see post#34 on page 2), and the other has a sort of scraper groove. Which one is correct if you back it up 1/8" and launch it in the barrel from afar?

[Tom Myers]

You know Tom, I'm starting to get real jealous of that program ya got there. Sure makes pretty pictures!
Thank you for doing this!

OK, so we have two theoretical options that Tom has drawn up.

One has a tapered lead in (see post#34 on page 2), and the other has a sort of scraper groove. Which one is correct if you back it up 1/8" and launch it in the barrel from afar?

Tim,
No need for you to suffer through those agonizing and debilitating pangs of envy and jealousy.
All it takes is a few bucks and a little bit of your time and you too can download and enjoy the benefits of the Cast Bullet Design software packages.


If one were to "Back up" either design in the chamber, the theroetic three point alignment concept of the designs would be lost, thus allowing either or both non-concentric bullet slump or initial bullet, bore axis misalignment.

[btroj]

First off you need to realize that fit in a lever action won't be the same as in a bolt gun. Think of what Run said, no camming to push bullet into lands. Your rifle also won't feed a bullet that can fit like a bolt action could.

Look at that link I sent. Eutectic mentioned ONE way of getting awesome dynamic fit with his single shot where the bullet is pretty my entirely in the throat at ignition. Great example, not practical.

Getting good dynamic fit will require matching powder curve and alloy. It will require a bullet that can self center. Remember my comment he other day about my Marlin 357? The 640 style nose gave me better results than anything because it gave better dynamic fit. That gun has a long, but abrupt throat. Square shouldered bullets need not apply.

You are pushing a bullet into a tapered hole. What will go in easier and to straighter, a squared shouldered bullet or one with a tapered nose? Will the taper angle make much difference? I like a tangent ogive, I think it gives the best entry into the throat.

Don't forget that your bullet deformation tests were all in a different rifle with low pressure charges. Different gun with higher pressures will make the bullet far more plastic, need to take that into account.

[btroj]

You know Tom, I'm starting to get real jealous of that program ya got there. Sure makes pretty pictures!
Thank you for doing this!

OK, so we have two theoretical options that Tom has drawn up.

One has a tapered lead in (see post#34 on page 2), and the other has a sort of scraper groove. Which one is correct if you back it up 1/8" and launch it in the barrel from afar?

Don't forget to look at how those bullets will fly. Both are essentially a long wadcutter. I doubt they will give great results at ranges past 50 yards.

Feeding and downrange accuracy can't be ignored.

Trading downrange capabilities for potential accuracy isn't a good trade in my opinion unless you want a short range tack driver.

[MBTcustom]

Let's not lose focus here Brad. The whole reason I started this thread was to have a good discussion and figure a few things out. Mainly: What is the best compromise that can be made with the angles and such in order to get the best possible scenario from a lever gun with a chamber such as this.
I am very very aware that the situation in this rifle is different from a bolt gun. That's why I started the thread.
Please consider that if you don't get a boolit launched correctly to start with, it really doesn't matter how aerodynamic it is does it? I pretty boolit that misses really doesn't do much for me.

Now, I have a few 44 boolit designs kicking around the shop, and I picked one that was the closest to Tom's awesome, sexy, bodacious and incredibly kewl depiction up yonder.
Happens to be this RN Ideal I was already dinking with.

OK, so I went to the sand box and started messing with cat sneeze loads to see what I could figure out about fit.
I tuned the load so that I could stop the boolit in the throat, so I could then see if the boolit was centering itself or not. Obviously, if the first driving band of the boolit could not center itself at low pressure, there is not a snowballs chance in hell that it would do it at max speed. Just to make the test fair, I used some boolits that were cast out of a very hard WD alloy on the order of 19BHN.

What I found was that the boolit was not centered in the throat at all.
This is one side, and you will notice (OK, maybe you can't see it) that the lands cut deep enough to wipe the surface of the boolit with the grooves?
Attachment 111813
Directly opposite, we see that the lands did not cut as deep, and also extended all the way down to the bottom driving band.
Attachment 111814

Conclusion: That boolit entered the rifling crooked.

[btroj]

That bullet doesn't hit the rifling until it is the full diameter. What happens of the nose had a more gradual taper along the joint from more to bore diameter?
A round nose doesn't have much for self centering properties. The nose never makes any contact with anything.

Are you interested in a purely academic discussion of fitting this rifles throat or in making a practical bullet that shoots well, feeds, and has downrange potential?

From a purely academic approach Tom gave the answer. From a practical point of view it is lacking.

[MBTcustom]

Are you interested in a purely academic discussion of fitting this rifles throat or in making a practical bullet that shoots well, feeds, and has downrange potential?

From a purely academic approach Tom gave the answer. From a practical point of view it is lacking.

Aha! but academics are useless without application are they?
Academics can be used as a crutch with a bolt gun, but not with this scenario. In this scenario, academics and theory is going head to head with "the real world" and I hope to gain a better understanding of how to balance the two to produce the best possible outcome.

I already know how to get a usable load from this that will do for busting deer etc etc, but I want to use this rifle to learn about dynamic fit and how things work at launch. Nothing like this will ever be made in my shop, as I am persnickety about building superbly accurate rifles (as you are about to find out) and this is the perfect place to do some experiments.
Besides, this rifle was presented to me by Felix's family, and I feel there is no better honor I could do a rifle from that man as to use it to learn something important.
Felix did things like this. He looked closer than most people were willing to, at things that other people didn't think mattered, and he always seemed to know more than everybody else.

SO, in honor of Felix, I am continuing on. If I'm boring everybody tears, there's a whole bunch of other things to read than my little project here, but I really appreciate the time you take to discuss this and look a little deeper.
I'm not looking for a quick answer to anything. I'm trying to learn about boolit design. That's it.
Thanks!

[btroj]

Contact someone like Blammer that has a huge variety of 44 cal moulds and get a dozen or so from each. Look at how they fit and look after your sandbox test. Which nose shapes center best.

I'm sure Rick has a few designs too but his might be designed for best work in a revolver and might not be best in a rifle like yours.

Welcome to the world of leveractions. I have been fortunate to only have get real picky on me. Or maybe I just got lucky and chose the right design up front?

[MBTcustom]

I'm going to start cutting boolits out of billet lead with different nose profiles and see what I can determine.